The book begins with a psychopath named Kimmel following his wife’s bus as she’s attempting to leave him. The first time the bus stopped, he brutally murdered her, but has set up something of an alibi. Walter Stackhouse, a handsome well to do lawyer, reads about this and intuits what happened even though the crime was attributed to a drifter. He himself is in an unhappy marriage. His wife commits suicide, but the similarities to her death and Kimmel’s wife put Stackhouse under suspicion. He is not guilty of the murder but acts more and more like he is. It all unwinds from there.
This is territory Highsmith returned to in the much better later novel A Suspension of Mercy. In both cases, it is somewhat difficult to believe that people acted in the way the protagonists did, considering they were otherwise intelligent people. But in the later book the characters were more well drawn out and the insights into human behavior were sharper. The Blunderer is good, but is probably my least favorite among the Highsmith I’ve read.